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Sir: Dr. Jeffrey Mattes’s criticism of the power analysis in
our study is, in part, well taken, if we did not make it sufficiently
clear that dropouts were considered in our original
power analysis.

We had calculated that it was necessary to recruit 40 subjects
per treatment arm in order to achieve 80% power with an expected
25% dropout rate. However, we were unable to recruit
more than 21 and 19 patients in the clozapine and olanzapine
arms, respectively.​